1. Field of the Invention
The invention generally relates to cryostats for use in conducting experiments, and more particularly to a low cost cryostat for facilitating a serial interfacing of experiments with a single cryostat in a substantially gravity-free environment, commonly referred to as a Zero-G environment, for the sake of convenience hereinafter simply referred to as a gravity-free environment.
As is fully understood, helium may exist as a gas, or in a normal liquid state, also referred to as helium I, as well as in a super fluid state, herein referred to as helium II, depending upon the pressure and temperature thereof. While the thermal conductivity of helium II makes its use potentially desirable in the field of cryogenics, from a practical standpoint, its lack of any capacity to store heat tends to severely penalize its use for this purpose.
2. Description of the Prior Art
As can be fully appreciated by those familiar with the problems encountered in conducting experiments at cryogenic temperatures in a gravity-free environment, the carrying out of conventional experiments tends to be relatively expensive, particularly in instances where helium is used as a coolant. The expense, at least in part, is a consequence of the complexity of systems required for maintaining experiments in a liquid helium environment. Moreover, it heretofore generally has been accepted that a changing of experiment packages, within a given cryostat, cannot readily be accomplished in a gravity-free environment such as is found aboard an operating spacecraft. Therefore, experiments cooled using liquid helium as a coolant frequently are returned to earth in tact, thus requiring that for each experiment to be performed, a new set-up must be fabricated before launch.
Because of the long recognized aforementioned inadequacies of the prior art devices, there currently exists a need for a cryostat through use of which a number of experiments can be performed in a gravity-free environment utilizing a common mother or helium supply dewar and a plurality of daughter or experiment dewars, so that a series of experiments easily and quickly can be interfaced with the helium supply dewar, all without requiring fabrication of a new set-up for each of the experiments.
During the course of a preliminary search conducted for the invention hereinafter more fully described, the following patents were discovered:
______________________________________ Fulton, Jr., et al 3,004,394 Oct. 17, 1961 Latterner, et al 3,168,080 Feb. 2, 1965 Byrd 3,548,930 Dec. 22, 1970 Katz 3,596,713 Aug. 3, 1971 Chu, et al 3,609,991 Oct. 5, 1971 Sturm, et al 3,688,838 Sept. 5, 1972 Beaussay, et al 3,824,598 July 16,1974 Basiulis 3,884,296 May 20, 1975 ______________________________________
While the patents discovered in the course of the search clearly indicate a use of numerous systems employing helium as a coolant, for performing cooling functions of a varied nature, none of the references discovered in the course of the search suggest a system which embodies the principles of the invention, hereinafter described with more particularity.
For example, United States Letters Pat. No. 3,004,394 discloses a helium heat rectifier which will conduct heat in a first direction when a temperature differential is established across the device, but will not conduct heat in opposite directions. United States Letters Pat. No. 3,884,296 discloses a heat pipe confining a cryogenic working fluid such as oxygen, liquid nitrogen and freon and is considered to be of interest. The remaining references were selected simply because they are believed to be of general interest.
It is, therefore, the general purpose of the instant invention to provide a low cost cryostat of a practical design which facilitates faster turn-around time, and generally tends to reduce the costs normally incurred in conducting experiments at low cryogenic temperatures in gravity-free environments.